Child resistant closure devices for containers having a threaded neck are known and are described, for example, in U.S. Pat. Nos. 3,733,000; 3,809,274; 3,924,770; and 3,946,890 issued to Scuderi on May 15, 1973; May 7, 1974; Dec. 9, 1975; and Mar. 30, 1976, respectively. Each of these patents describes a closure device including a screw type cap and a drive member which fits movably over the cap. The screw type cap, often an inner cap, has a first circle of teeth on the side wall of the cap. The drive member, often an outer cap that fits over and around the inner cap, has a second circle of teeth adapted to engage the first circle of teeth when the drive member is pressed firmly in the direction of the inner cap. It is, therefore, necessary to simultaneously press and turn the drive member in order to unscrew the cap. Such closure devices are considered to be child resistant since it is unlikely that a small child would appreciate the necessity for simultaneously pressing and turning the drive member and, even if this is appreciated, a small child is unlikely to have sufficient strength to perform these functions simultaneously.
Child resistant closures such as those described in the Scuderi patents are not "tamper-evident", meaning that they do not include means which indicate if the container has been opened after leaving the factory and prior to purchase. This raises the possibility that the contents of the container can be tampered with prior to use by a consumer without the consumer knowing. Since many child resistant caps are used with medications, it is desirable that the cap produce an indication of unauthorized opening of the container.
U.S. Pat. Nos. 3,837,518 issued to Gach on Sept. 24, 1974 shows a child resistant closure with a tamper-evident feature. The Gach closure includes an inverted cup-shaped inner cap and an outer overcap. A tamper-evident tear strip forms part of the overcap skirt and rests against a shoulder on a bottle. This prevents downward movement of the outer cap, which is required for transmitting bottle opening rotation to the inner cap. Accordingly, co-operating clutch means on the inner and outer caps of a Gach closure cannot be engaged until the tamper-evident tear strip is removed.
However, operation of the Gach closure is dependent upon the configuration of the container on which it is used. Specifically, the closure does not function for its intended purpose unless the container has a shoulder so positioned that when the Gach closure is closed the tear strip must abut against the shoulder to force and hold the outer cap up and thus prevent engagement of the clutch. There are numerous other patents which also disclose a child resistant cap with a tamper-evident feature.
None of the prior art, however, teaches or suggests a tamper-evident child resistant closure device formed of an inner cap and an outer cap wherein means for preventing engagement of a first circle of teeth on the inner cap with a second circle of teeth on the outer cap is provided in such a way as to be independent of the container configuration for its operativeness.
It is, therefore, an object of the invention to provide a tamper-evident child resistant closure device which does not require a special bottle configuration.
Another object of the invention is to provide a simple tamper-evident child resistant closure device.
A further object of the invention is to provide a tamper-evident child resistant closure device which can be readily installed on a bottle during a manufacturing process.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.